Valve for rock drills



Oct. 7, 1930.

W. A. SMITH, JR

VALYE FOR ROCK DRILLS Filed DeC. l2, 1929 &

Fig-2 IN VEN TOR.

.Hf/5 ATTORNEY.

j by the distribution o' W'LLIU/l A. SMITH, GR., 0F FHLLISBRG, NEV JERSEY, ASSIGNOR TO NGERSGLL- RAND CQMPANY, 0l? JERSEY CETY, NEW' JERSEY, [i CORSORATON 0F NEW JERSEY VALVE FOR RGCK DRELLS Application filed Becenioer This invention relates to fluid actuated rock drills, but niore particularly to a distributing valve for drills of this type.

' @ne object oit the invention is to obtain a 5 quick and positive action of the Valve and consequently a rapid distribution of rpressure fluid to the cylinder for actuating the piston.

@ther objects will be in part obvious and in l0 part pointed out hereinafter.

ln the drawings illustrating the invention and in which similar reference characters refer to siinilar parts,

Figure l is a sectional elevation of a porl5 tion of a roch drill equipped with a Valve conf l ing the valve in another limiting position.

Referring niore particularly to the drawings, A designates a cylinder having a piston chamber il in Which is disposed a reciprocatory hainnier piston C.

A front cylinder Washer D forins a closure Jfor thefront end of the piston chamber B and also serves to centralise a front head E with respect to the cylinder A..

The front hea l E is suitably bored to guide working iinpleinent F, the rear end ot which Xtends into a cavity G in the rear end of' the bont head E to receive the blows of the ham-- fier pistonv C and which blows are this intance transmitted to the Working implement ...4" by anvil block H guided by the front cylinder Washer D.

in the rear end of 1the cylinder is a Valve ine ianisin designated generally by J Wherei pressure fluid to the i ton chamber B is ffected. The valve mechanism J comprises a pair of plates K and L which forni the Valve chest and in said plates K and L is a Valve chaiiiber O to acconirj niodate a distributing valve P.

The plate l: is disposed adjacent the rear end of the piston chamber B to forni a closure therefore. The plate L is seated on the plate l and in turn serves as a seat for a back head te Q. which ina he suitably secured to the cylin- NQ Scal No. 413,535.

der il as by ineans of the usual side bolts (not shown).

The back head Q serves as a closure for the extrenie rear end of the cylinder A and also acts as a housing for a rotary throttle Valve lt having a chaniber S into which pressure fluid inay be constantly admitted troni a suitable source of supply. ln the Wall or" the throttle valve. l is a port T which registers With a passage U located in the back head Q and opening into the rear end of the valve chaniber 0.

The pressure fluid utilized. for actuating the piston C forii'ardly is conveyed to the rear end of the piston chaniber B by rear inlet passages V which have their inlet openings in the front end of the valve chamber 0. i front inlet passage Vf leads freni a point near the rear end of the valve chainber O through the plates K and L and the cylinder A to the front end of the piston chamber B. The exhaust of fluid from the piston chaniber to the atmosphere is effected through a free exhaust port X in the cylinder A and controlled by the piston C.

T he Valve P is of thc hollow type through which pressure fluid flows to one of the inlet passages, in this instance to the rear inlet passage or passages V. The valve accordingly has a recess Y which is constantly supplied with pressure fluid troni the rear end of the 'valve chamber O. ln the front end or Wall of the if: ylife P is a port Z through which pressure fluid flows freni the recess Y to the inlet iassagcs V.

The rear end of the valve P is in the form of :t stein Zi which controls the inlet passage W and on the rear end of the stein is a pressure surface c which is constantly exposei'l to pressure fluid tending to throw the valve forii'ardljif. The opposite or front end of the valve constitutes a pressure surface d against which compression from the rear end of the piston chamber B may act tending to throuv the Valve P rearwardly.

r" d.ditioiial ineans are provided to assist in throwing the valve P rearwardly. To this end the valve P is provided with a flange e having an actuating` and holding surface 7 at its front end against Which pressure fluid intermittently acts to assist the compression acting against the pressure surface Z to throw the valve P rearwardly. The pressure fluid utilized for this purpose is conveyed to a pressure chamber g wherein the flange e is disposed through a constant leak passage and through a trip passage j which opens with one end into the pressure chamber g and with its other end into the piston chamber B at a point slightly rearwardly of the exhaust port X.

The inlet opening of the leak passage 71, is so arranged that it is in constant communication with the port Z in the piston and said passage h opens with its other end into the trip passage Preferably the pressure acting against the actuating surface f is immediately reduced after the valve P has been thrown rearwardly and for this purpose an exhaust passage 7c is formed in the plate K and the cylinder A to afford communication between the pressure chamber g and the atmosphere. The passage 7c is so located that it will be uncovered by the flange e as the valve P approaches its rearxnost position.V

In order to prevent a cushioning effect against the rear surface of the flange e a vent o is formed in the plate K and in the cylinder A to constantly open the rear end of the pressure chamber' g to the atmosphere.

The operation of the device is follows: lVith the valve P and the piston C in their rcarniost positions illustrated in Figure l, pressure fluid will flow from the throttle valve Il into and through the valve P and through the front end of the valve chamber O and the inlet passages V into the rear end of' the piston chamber B to impel the piston C forwardly against the anvil block H.

During the time the piston is in its rearniost position and until slightly prior to the time it uncovers the exhaust port X the pressure fluid flowing through the leak passage h into the trip passage j will be entrapped therein since then the piston C will cover the trip passage Such pressure fluid will act against thc actuating surface and will assist the pressure lluid acting against the pressure surface (l to hold the vaive rearwardly.

the piston C proceeds Jforwardly itwill will uncover first the trip passage j and then the exhaust port X to permit the exhaust oi pressure fluid from the rear end of' the piston chamber B well as that in the pressure chamber g, to the atmosphere.

Upon this reduction in pressure against the surfaces d and f the pressure fluid acting against the pressure surface c together with the suction created by the pressure fluid during its passage through the port Z will throw the valve forwardly to uncover the inlet passage W. Pressure fluid will then flow into the front end of the piston chamber B to return the piston C to its initial position.

During the rearward travel of the piston C said piston will again cover the trip passage so that the pressure fluid flowing through the leak passage L into the trip passage y' will be entrapped in the pressure chamber g to assist the compression acting against the pressure surface d to again throw the valve P rearwardly.

I claim:

l. In a fluid actuated rock drill, the combination of a cylinder and a piston therein, a valve chest having a valve chamber, inlet passages leading from the valve chamber to the cylinder, a valve in the valve chamber through which pressure fluid flows to one inlet passage, a stem on the valve and over which pressure fluid llows to the other inlet passage, a pressure surface on the valve against which pressure fluid constantly acts for throwing the valve in one direction, an opposed pressure surface on the valve against which compression acts tending to throw the Valve in the opposite direction, au actuating surface on the valve, and a trip passage in constant communication with a source of pressure fluid supply and controlled by the piston to intermittently7 expose the actuatingsurface to pressure fluid to assist the compression in throwing the valve.

2. In a Huid actuated rock drill, the combination of a cylinder and a piston therein, a valve chest having a valve chamber, front and rear inlet passages leading from the valve chamber to the cylinder, a hollow valve in the valve chamber through which pressure fluid flows to the rear inlet passage, a stem on the valve and over which pressure fluid flows to the front inlet passage, a pres-- sure surlace on the stem constantly exposed to pressure fluid tending to move the valve to a position to uncover the front inlet passage, an opposed pressure surface subjected to compression tending to move the valve in the opposite direction to uncover the rear inlet passage, a flange on the valve having an actuating and holding surface, and a trip passage in constant communication with a source of pressure fluid supply and with the actuating surface and the cylinder and controlled by the piston to intermittently expose the actuating surface to pressure fluid to assist the compression throwing the valve and for holding the valve noment-arily stationary.

In testimony whereof I have signed this specication.

WILLIAM A. SMITH, JR. 

